Safety control device for disconnecting switches



y 1947- c. P. COREY ET AL 2,420,166

SAFETY CONTROL DEVICE FOR DISCONNECTING SWITCH Filed March 1, 1946 INVENTORS GfimcntP 602a zf'azfli Deming Patented May 6, 1947 SAFETY CONTROL DEVICE FOR DISCON- NECTING SWITCHES Clement P. Corey and Earl R. Deming, Millbury, Mass.

Application March 1, 1946, Serial No. 651,202

. 6 Claims. 3

This invention relates to switches used in power plants and elsewhere for disconnecting or cutting* out a section of a power line for changes or repairs or other desired purpose. Such disconnecting switches are not designed to be opened under load. If so opened, a heavy arc may occur, with more or less disastrous results.

In order to prevent such occurrence, it is now customary in power plants to require that all such switches be first opened for a short distance only. If no arc occurs, the line may be assumed to be dead and the opening movement may be coinpleted. If the line is alive, a relatively short are will occur and the switch can be immediately closed and damage avoided. The human element remains, however, and switches are occasionally thrown wide open, regardless of rules, and with serious results if on live circuits.

It is the general object of our invention to provide a control device which -makes it impossible to open the associated disconnecting switch otherwise than by the step-by-step procedure above outlined.

To the attainment of this object, we provide means to lock the switch after it has been opened a small amount only, and to unlock the switch for further opening movement by a slight return movement of the switch bar from its locked position. We also provide a construction in which an parts are restored to initial position by fully closing the switch.

Our invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which Fig. 1 is a side elevation of a disconnecting switch with Our improved safety device applied thereto;

Figs. 2 and 3 are partial side elevations similar to Fig. 1 but showing the parts in successive operative positions;

Fig. 4 is an enlarged side elevation of a cam and lock plate; and

Fig. 5 is a detail side elevation showing a modified construction.

Referring to the drawings, we have shown a disconnecting switch having brackets or stands Ill and II mounted on insulators 12 which in turn are secured to a base plate It. Studs 15 and nuts iii are provided for connecting line wire terminals to the stands I0 and II. A switch bar 20 is pivoted at 2! to the stand Ill and is normally seated between spaced side portions of the stand.

l l. The bar it is held in closed position 'by a ilug 2-2 formed one. handle member 23 and received in a notch 2 in thestand H. The handle :member 23 is slidably and yieldably mounted on the :bar 2% and may be pulled outward to disengage the lug '22 when the switch is to be opened. All of the parts thus far described are of usual com-- mercial construction and in themselves form no part of our invention.

Our improved safety device comprises a cam and lock plate 3i! '(Fig. 4) and a locking lever 3| (Fig. l). The cam plate 30 is secured to the side of the stand Hi and is retained in position by the pivot stud 2i and by a screw -3i'a which also secures a'cover plate 32.

The lever 3| is provided with a slot 40 in its upper end and is mounted on a stud 4| in a slidable support 42. The support 42 may be adiusted lengthwise of the bar 26 and may be secured in any desired position by tightening the clamping screws 44.

The cam plate 30 has a cam surface 45 and a locking lug or holding projection 46. The lever 31 has a hook 4'8 and a cam surface '49. A coil spring is connected at one end to a stud 5| in the support 42 "and at the other end to the lever 3| at a point 53. The point 53 is 'so selected that when the lever 31 is in the position shown in Fig. 1, the spring will tend to raise the hook 48, and when in the position shown in Figs. 2 and 3, it will tend to-depress the hook d8.

Having described the construction of our improved safety devicathe operation thereof is as follows:

When the switch bar 29 is moved to closed position, the cam surface 49 of the lever 3| engages the cam surface 45 (Fig. 4) of the cam plate 30 and the lever M is shifted upward and to the right relatively to the bar 29, the parts assuming the position shown in Fig. 1.

As the *bar 25 is thereafter raised, the hook it will engage the lug 46 and the lever 3| will be shifted relatively to the bar 28 to the position shown in Fig. 2, in which position the bar 20 is locked against further opening movement.

During this shifting of the lever 3| relative to the bar 25, the point of connection 43 between the lever 3i and the spring 59 has shifted to the left, as also shown in Fig. 2. The bar Ell may then be given a slight return movement to the position shown in Fig. 3, if no arc has been formed between the bar 2%) and the stand H on the initial opening movement.

On such return movement, the spring 59 will cause the hook 48 to drop below the lug 46. The

locking device is thereby disengaged and the swinging upward movement of the switch bar 20 may be completed.

When the switch is thereafter closed, the parts first return to the position shown in Fig. 3. The cam surface 45 thereafter coacts with the surface 49 on the end of the lever 3| to shift the lever 3| back to the position shown in Fig.1, thus completing the cycle of operations.

We have thus provided positive and mechanical locking means by which a disconnecting switch can be opened only by a step-by-step procedure, with a short initial opening movement followed by a slight return movement before the opening movement can be completed. With our improved safety device in operation, no dependence need be placed on the memory or good intentions of the operator, as the switch cannot be opened except by following the outlined procedure.

In the modification shown in Fig. 5, the construction and operation is the same as previously described, except that a flat compression spring 60 secured at BI is substituted for the tension coil spring 50 previously described. As the spring 60 is in compression rather than under tension, the spring 69 is mounted above the looking lever 62 rather than below the lever as in Fig. 1. The operation, however, is identical Having thus described our invention and the advantages thereof, we do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what We claim is:

1. In a disconnecting switch having a stand and a switch bar pivoted thereto, in combination, a locking projection fixed to said stand,

' a locking lever pivotally and shiftably mounted on said switch bar and having a locking hook at its free end, and a spring shiftable with said lever to opposite sides of the pivot of said lever and effective to move said hook toward said projection when said switch bar is in closed position and to move said hook away from said projection after said lever has been shifted longitudinally by locking engagement and after said hook has been freed from said locking projection by slight and partial return movement thereof.

2. The combination in a disconnecting switch as set forth in claim 1, in which a fixed cam plate is provided which coacts with the free end of the locking lever to move the hook on said lever into position to engage the locking projection on the stand on return of said switch bar to fully closed position.

3. The combination in a disconnecting switch as set forth in claim 1, in which the locking lever has a longitudinal slot through which a pivotpin on the switch bar extends, and in which the spring engages the lever adjacent said pin and is operative alternately at opposite sides of said pin as said lever is shifted longitudinally, whereby the spring action is reversed.

4. The combination in a disconnecting switch as set forth in claim 1, in which a fixed cam plate is provided which coacts with the free end of the locking lever to move the hook on said lever into position to engage the locking projection on the stand on return of said switch bar to fully closed position and which provides clearance for the hook to drop when freed from said projection and only partially returned to initial position.

5. The combination in a disconnecting switch as set forth in claim 1, in which the locking lever has a longitudinal slot through which a pivotpin on the switch bar extends, and in which a tension spring engages the lever adjacent said pin and is operative alternately at opposite sides of said pin to raise and lower said hook as said lever is shifted longitudinally to reverse the spring action.

6. In a disconnecting switch, a switch bar, means to lock said bar after predetermined and limited travel from closed position, said locking means being mounted for longitudinal shifting on said bar, and a single spring means effective to render said locking means alternately operative and inoperative in accordance with the longitudinal relation of the switch bar and the locking means.

CLEMENT P. COREY. EARL R. DEMING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,750,693 Steinmayer Mar. 18, 1930 1,825,820 Read Oct. 6, 1931 1,864,548 Nordhem June 28, 1932 1,253,286 Sierad Jan. 15, 1918 1,933,285 Strai Oct. 31, 1933 2,251,115 Crabbs July 29, 1941 

